Fusobacteriumnucleatum-Stimulated OSCC Cell-Derived Exosomes Induce a Pro-Adhesive Phenotype in Lymphatic Endothelial Cells via the ROS/NF-κB/ICAM1 Axis.

The role of Fusobacterium nucleatum (F. nucleatum) in regulating exosome-mediated communication between oral squamous cell carcinoma (OSCC) cells and lymphatic endothelial cells (LECs) remains poorly understood. Here, we confirmed the presence of F. nucleatum in OSCC tissues and showed that it induced inflammation- and vesicle-associated transcriptional changes in OSCC cells. Exosomes were isolated by differential ultracentrifugation, and quantitative analyses demonstrated that F. nucleatum stimulation increased exosome yield from OSCC cells. In vitro, pretreatment of LECs with exosomes derived from F. nucleatum-stimulated OSCC cells (Fn-Exo) enhanced OSCC cell adhesion to LEC monolayers. Fn-Exo upregulated intercellular adhesion molecule 1 (ICAM1) expression in LECs, and ICAM1 blockade partially reduced Fn-Exo-induced OSCC cell adhesion to LECs. Fn-Exo increased intracellular reactive oxygen species (ROS) accumulation and promoted NF-κB p65 phosphorylation and nuclear translocation in LECs. N-acetyl-L-cysteine (NAC) attenuated Fn-Exo-induced ROS accumulation and NF-κB activation, and both NAC and the NF-κB inhibitor BAY 11-7082 reduced ICAM1 upregulation and partially attenuated the enhanced adhesion of OSCC cells to Fn-Exo-treated LECs. These pharmacological inhibition experiments support the involvement of ROS/NF-κB/ICAM1 signaling in the Fn-Exo-induced pro-adhesive phenotype. Collectively, these findings indicate that F. nucleatum is associated with increased exosome yield from OSCC cells and that Fn-Exo enhances the adhesive interaction between OSCC cells and LECs.